1. Field of Invention
The present invention relates to a fan and a fan frame thereof, and in particular to a fan and a fan frame thereof that can lower the noise and increase the efficiency.
2. Related Art
The efficiency of a fan is indicated by the air pressure and air volume that it can generate. To increase the air pressure and volume, one method is to increase its rotation speed. However, noises come with high-speed rotations. To solve this problem, the prior art modifies the design of blades. Nevertheless, this method is both difficult and impractical. In the overall structural design of the fan, changing the fan frame is another way of promoting the fan efficiency.
FIG. 1 is a cross-sectional view of a conventional fan 1, which has a fan frame 10. The fan frame 10 includes a housing 103, a base 104 and at least one connecting element 105 connecting the housing 103 and the base 104. The fan frame 10 also has an inlet 101 and an outlet 102. The base 104 is disposed at the outlet 102. The housing 103 has a first guiding angle 108 and a second guiding angle 109 at the inlet 101 and the outlet 102, respectively. The first guiding angle 108 and the second guiding angle 109 are slant surfaces for guiding the airflow in and out.
However, as the airflow is guided into the fan through the inlet 101, the airflow is directly guided out afterwards because the base 104 is a vertical structure. That is, the pressure of the airflow is not increased. Moreover, when the airflow passes by the outlet 102, the slant surface design of the second guiding angle 109 guides it out without any merging effect. After the airflow leaves the outlet 102, a vortex is produced at the outlet 102, which results in noises so that a negative effect on the efficiency of the fan is induced.